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Physics problem help please

  1. Jan 20, 2008 #1
    1. The problem statement, all variables and given/known data


    mappy.jpg

    in this attachment is a moments problem could someone please help me solve it

    the question is
    a) using moments find F1
    b)using any method find F2

    thank you
     
  2. jcsd
  3. Jan 20, 2008 #2

    arildno

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    Since your attachment is not yet visible, there is little WE can do as yet, given your minimal descriptions of your problems.

    You, however, can alleviate that by describing the problem in sufficient detail.

    Furthermore, we have a policy that we don't do your homework for you.
    That means you need to say what you have done so far, and identify those part issues you are struggling with.

    Until you have shown your own work, you won't get any help.
     
  4. Jan 20, 2008 #3
    zoom in

    it is visible you just have to zoom in

    it shows my attempt but i don't think it is right

    any help i would be grateful
     
  5. Jan 20, 2008 #4

    Doc Al

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    FYI: Attachments need to be approved by a moderator before anyone can see them. Be patient! :smile: (It should be viewable now.)
     
  6. Jan 20, 2008 #5
    ok i'm verry sorry i'm new so i didn't know they haveto be approved
     
  7. Jan 20, 2008 #6

    arildno

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    I'm sorry, your attachment is illegible, at least on my screen.
     
  8. Jan 20, 2008 #7
    do you know why?
     
  9. Jan 20, 2008 #8

    Doc Al

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    Zoom in on it. (Just click it to enlarge it.)

    FYI: Your attachment is not self-explanatory. Decribe the problem exactly as given and how you attempted to solve it. Use the diagram as supporting material.
     
    Last edited: Jan 20, 2008
  10. Jan 20, 2008 #9
    i haveto find F1 and i think the best way is to use F2 as the pivot so you automaticaly eliminate F2, then taking clockwise and anticlockwise moments, but that is where i got confused and am not totally sure how to do that part.
     
  11. Jan 20, 2008 #10

    Doc Al

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    Describe the problem a bit more. I don't know how to interpret the diagram yet. Is there some kind of plank? I assume that three forces act on the object: F1, F2, & W? Is the object in equilbrium? Do any other forces act?
     
  12. Jan 20, 2008 #11

    arildno

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    Where is this thing attached? Is one end free? Or are both attached?

    Is W indicative of the centre of mass, or some mass particle just placed there in addition to the beam(?).

    This is too vague and unspecific to make sense of..
     
  13. Jan 20, 2008 #12
    its basically like a diving board a long plank and then on the left side theres 2 supports which are 0.8m apart and there is an extra 0.1m on the left side of the first one, W is the weight of the plank and is in the centre of the plank
     
  14. Jan 20, 2008 #13

    arildno

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    Okay, picture understood!

    So, the diving board is ATTACHED to the point where F1 is, agreed?

    In that case, ask yourself:
    In which direction should F1 act?
     
  15. Jan 20, 2008 #14

    Doc Al

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    I don't see anything wrong with your solution except the direction of F1. Which way must it point?

    (Edit: Too many cooks in this kitchen. You are in good hands with arildno! :wink:)
     
  16. Jan 20, 2008 #15
    i dont understand what is acting clockwise and what is acting anticlockwise
     
  17. Jan 20, 2008 #16
    i think F1 is the reaction force but wouldnt' that be the same as the force of F1 acting downwards according to Newton's 3rd law
     
  18. Jan 20, 2008 #17

    arildno

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    Don't bother about the clockiness of the moments for now, focus on the direction of FORCES.
     
  19. Jan 20, 2008 #18

    arildno

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    Do you agree that F1, the force acting upon the diving board from the support must be downwards in direction?
     
  20. Jan 20, 2008 #19
    yes, ok it's downwards maybe that was my mistake
     
  21. Jan 20, 2008 #20
    do you think my solution is correct then
     
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